The invention relates to a gearing and, more particularly, a single stage gearing.
The prior art has disclosed gearings which, by means of a selective engagement of teeth of a toothed ring into an internal toothing, can attain high transmission ratios of for example 1 to 50 or 1 to 100 in a single stage. An example of such a gearing is that disclosed in DE 10 2006 042 786 B4. Furthermore, under the name “harmonic drive”, gearings have become known which are of similar design to the gearing disclosed in DE 10 2006 042 786 B4, but the harmonic drive gearings have flexible toothed rings and not individual teeth which can move separately from one another.
Gearings having individual teeth which can move independently of one another have the advantage that high torques can be transmitted because the teeth need not be produced from a flexible material, as is the case in harmonic drive gearings. However, a transmission of torque by means of individual stable teeth has limits, in particular on account of the fact that there is always only in each case a very limited number of teeth in active engagement, for the purpose of transmitting torque, with an internal toothing of an internal gear.
One option for increasing the transmissible torques is to increase the diameter of the internal gear and therefore of the gearing. A further option is to increase the width of the teeth, that is to say the extent of the teeth in the axial direction of the internal gear or of the gearing. An increase in diameter is not expedient for all gearings on account of the installation possibilities. Likewise, a widening of the teeth is possible only to a limited extent.
Within the context of the invention, embodiments are preferable in which a plurality of toothed rings are provided. Here, however, the problem can again arise that, on account of torsion of parts of the gearing, the individual toothed rings are subjected to different loadings, such that the limit load of the gearing, that is to say the greatest torque that can be transferred, is determined by the then most heavily loaded toothed ring. This is ineffective.
It is an object of the invention to specify a gearing by means of which the disadvantages of the prior art are eliminated or at least alleviated. In particular, it is an object of the invention to specify a gearing which has a high transmission ratio and which, while having a small diameter, can transmit high torques.